System Description

1972 Exc. California

The deceleration control system on these models is a three part system. One part controls throttle opening during deceleration, another part acts to retard spark during deceleration and a third part retards the spark during engine idle.

A vacuum control valve is the component which controls both the spark retard and the throttle opening during deceleration. The vacuum control valve senses the higher Intake manifold vacuum and activates both systems. The throttle opening system uses a servo diaphragm assembly connected to the primary throttle shaft. During deceleration, the vacuum control valve opens to allow vacuum to be applied to the servo diaphragm. The diaphragm then moves to open the primary throttle plate slightly and feeds additional fuel to richen the mixture.

The spark retard system uses a dual point distributor and a vacuum switch. During deceleration, the vacuum control valve opens to allow vacuum to be applied to the vacuum switch. The vacuum switch then closes and activates the retard breaker points in the distributor to retard the spark. During acceleration and normal operation, the spark is controlled by the standard breaker point set. During deceleration, the standard breaker points are by-passed and the spark is controlled by the retard set. This retard circuit retards spark advance 7-10 degrees, decreasing engine speed.

During engine idle, the accelerator switch controls the retard points in the distributor. When the engine is running above idle, the accelerator switch is open and the distributor operates on the standard breaker point set. When the accelerator pedal is released, the switch is closed and the retard breaker point set is activated, retarding spark advance.


1972 California & 1973-82

This system maintains a balanced air fuel mixture during deceleration.

Fig. 13 - Deceleration Control System:

This system on 1972 California and 1973-76 engines consists of an air control valve, anti-afterburn valve and a coasting richer valve, Fig. 13.

This system on 1977-78 1.8 liter engines except California, consists of an anti-afterburn valve, dashpot and a throttle opener system that is composed of a servo diaphragm connected to the throttle lever and a vacuum control valve.

This system on 1977-78 1.8 liter California engines consist of an anti-afterburn valve and a throttle position system composed of a servo diaphragm connected to the throttle lever and a vacuum control valve.

This system on 1977-78 2.3 liter engines except California, consist of an air bypass valve, a dashpot on manual transmission equipped models, and a coasting richer valve which is actuated by vehicle speed and the accelerator switch.

This system on 1977 2.3 liter California engines consists of an air bypass valve and a dashpot on manual transmission equipped vehicles.

This system on 1977-82 2.3 liter California engines consists of an air bypass valve, a dashpot on manual transmission equipped vehicles and a coasting richer solenoid valve which is actuated by vehicle speed and an accelerator switch.

This system on 1979-82 2.0 liter engines except California consist of an anti-afterburn valve and a throttle positioner.

This system on 1979-81 2.0 liter California engines, consist of an air bypass valve and throttle positioner.